The fact that she was just 15 when this happened speaks volumes to me. Iowa is so backwards it's messed up. It sounds like this was more to do with the laws on the books than anything.
I get that at some point it stops being self defense and becomes murder, but most people in said situation, if they were given the opportunity to fight back, they would and they probably wouldn't stop. I know if I was raped by someone, I would want blood. I think it's justified if something like that happens.
As well, when you're in such a situation, you're not going to think clearly, you're judgement will be clouded, so that in itself should be a defense. This woman deserves a much better defense team.